1. Field of the Invention
The present invention relates to an apparatus for forming an image on a copying machine at a variable zoom ratio with the aid of a zoom lens system.
2. Background of the Invention
A conventional apparatus of the type contemplated by the present invention that forms an image on a copying machine at variable zoom ratio is described in Unexamined Published Japanese Patent Application NO. 10214/1985. In order to enable displacement of the positions of the first and second lens groups, the apparatus employs a distance altering mechanism that is composed of pins engaging each lens group and a cam barrel having cam grooves into which the pins are fitted. The apparatus is so constructed that when the two lens groups are displaced en masse along the optical axis, the cam barrel is rotatably driven so as to alter the distance between the two lens groups. However, in order for the cam barrel to be rotated in synchronism with the movement of the lens groups, the apparatus requires a large number of components including a rack and pinion assembly, a motor and a worm gear. In addition, this apparatus does not allow for lens change.